Internal-combustion engine.



W. J. STILL. INTERNAL COMBUSTION ENGINE.

Patented Jan. 16, 1912.

. APPLICATION FILED APR. 14, 1911. 1,015,216.

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W. J. STILL.

INTERNAL GOMBU SIION ENGINE.

APPLIUATION FILED APR. 14, 1911.

Patented Jan. 16,1912.

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' W. J. STILL. INTERNAL COMBUSTION ENGINE.

APPLIOATIQN FILED APR.14, 1911v Patented Jan. 16, 1912.

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W. J. STILL. INTERNAL COMBUSTION ENGINE. 11 1 110111101: FILED APR.14, 1911.

Patented J an. 16, 1912.

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L'L JTERNAL-CQMBUSTIGN ENGINE.

Eipecificatton. 01' Letters Application filed ,tpril M, 1311.

"'3 whom may concern: AM, it known that i WILLIAM; dosnri-i grim, a suhicct of the of Great Brit- Southaii, in the county of Middle land have invented certain new and nal-Comh-ustion Engines, of which the lowing is a specification.

in another application tiled by me on the ain claims are made for lobed in this application and not claimed invention relates to internal com and "to constructions and arm of rotary valves for same, kind which embrace the cylindc'x This invention relates more particularly to operating on the tvv'o stroke cycle and. of the lzinc in which twocylinders each containing a pair pistons the two spaces between which form combustion chambers) piaced end to end and the inner pair of pistons-ware rigidly connected to one crank on crank shaft placed the end of the comhination and the other pair to other cranks on the shaft.

The object.- of the present invention to provide,iumroveinents resulting in the obof more complete and economical SHAH than heretofore and allowing of variation of thecompression as desireCv durrunuir or at any other time, Also i; L prociccd in which none c subjected to the in which the numper inin'sc ed are reduced obj cctw to wine oi the type rcto the cylinder is 1th 1- cut to the scavenging a rotary vaivc embrac ng the in a rotary engines cmi one or more other each ul L imroveu'icnts in and Relating to Ini i of jiprih 191i, vtimial No. 621,165, meet matter which faces co-act with ports connected on the one hand with the cylinder and on the other with gas ducts.

In applying this invention in one form to a gas engine as referred to above each cylinder may have in it three rings of ports, one ring at one end and two at the other. Of these the former will act as exhaust ports and of the two latter that nearest the center of the cylinder will act as gas and air mixture inlet and the other as the scavcng ing air inlet. The gas and air inletis controlled hy a rotary valve which embraces the cylinder and is adapted to remain closed until the piston has just closed the scavenging air ports and the exhaustports are just closing at which moment it commences to open. Part therefore of the charge enters by displacement of the air remaining and partby virtue of the inlet pressure and it therefore becomes practicable to employ a greater charge than the content of the cylinder at atmospheric pressure. Further more by retarding the opening of this inlet valve with relation to the closure of the exhaust valve a greater proportion of the mixture can be caused to enter by virtue of its pressure and the tnnpression of the charge may therefore be varled during running of the engine or at any other time means only being required for allowing alteration of the tuning of the valve in such a case.

A particular advantage of this arrangement lies in that the maximum period is given by the disposition of the scavenging air inletat the extreme end of the cylinder for the pressure in the cylinder to fall bye haustion before scavenging commences this leading to economical scavenging since-air at a lower pr ssure can be used and less of it necessary. As an example of such an arrangement of the periods may be given one in which commencing at the dead center ct one of the cranks the exhaust valve opens after 120 rotation, and remains open for 120", the scavenging air ports are uncovered l utter the exhaust ports and remain open until bet e the exhaust ports close at which momcntthc charge inlet valve opens and remains so for 85 when it is closed and compression connuenccs.

A. further feature of the present invention resides in an engine of the kind described of rods 5 and 71.

having in con unction with rings of ports concaved heads to the pistons of such curvature that eddy currents in the cylinder are avoided. I have observed by experiment that if the head of the piston which co-acts with the scavenging air ports issuitably concaved the inrush of 'air by these ports occurs in a uniform mass which does not mingle with theproducts of combustion but acts as a solid mass or wall to expel the same by pushing them along the cylinder, and there being no eddies much less air is required for complete scavenging by using this feature than is required where ordinary pistons are employed. It does not appear to be essential for both pistons where two pistons in a common cylinder are used to be so shaped. The preferred curvature is such that the radius of curvature of the head is the bore of the cylinder. Using the two features above set out I have succeeded in producing complete scavenging of a tandem engine of the kind indicated with air compressed only to two pounds to the square inch.

This invention also consists in the improved internal combustion engine and improved rotary valve hereinafter described.

In the accompanying drawings are shown one manner of carrying the present invention into efi ect.

Figures 1 and 1*, together illustrate in sectional elevation two units of a multi-unit two-cycle engine having tandem cylinders. Figs. 2 and 2 together show a side elevation of the same; and Fig. 3 a plan sectional view on the section line 11 of Fig. 1. Fig. 4t shows a sectional View. of the middle part of one of the cylinder pairs of the units on the section line 33 of Fig. 3.

Referring to these figures, a represents the cylinder castings which are connected together as shown in Fig. 4 by an intermediate member, Z). Each cylinder contains two pistons which are indicated in 1 by the reference letters 0, (l, c and f. The outer pistons, such as c and f, are rigidly connected together by a framework composed The inner pistons such as (Z and e are both screwed into an intermediate casting 2', through which passes a shaft j connected to rods 76 and Z. These rods in and l are connected to cranks m and 72, while the end piston, such as the nected by a gudgcon pin 0 and connecting rod 7) to a crank g on the crank shaft. An intermediate ball race '1" acts to support the crank shaft, and to prevent whipping of the same. Each cylinder is provided with three rings of ports, an exhaust ring such as s in Fig. 1, a ringof combustible inlet ports t and scavenging air ports u. The compressed gaseous combustible and the compressed air for scavenging are supplied to these ports. J The exhaust ports are unone e,"is con-- tible inlet ports, and provided with a series of passages in it co-acting on the one hand with the ports in the cylinder, and on the other hand with ports to (see F i) formed in the combustible supply duct. The combustible and air supply ducts comprise a hollow casting y forming ing around the engine, having passages in it for the air and for the mixture which enter the same by the air inlet 1 and the combustible inlet 2, having been previously compressed to the desired pressure. The air passes along the duct 3 in the hollow casting 7 and is distributed by an annular passage 4, to the air ports of each of the cylinders, as is shown in Fig. 4. The gas which enters at the inlet 2 sage 5, and directly through the ports '10, and the perforations in the rotary valve, which is suitably situated, into one of the cylinders, passing also by way of the ducts 6 and the ports 'w of the other cylinder when the othervalve is in suitable position. In this way, by the use of a single hollow casting and ducts such as are indicated both cylinders are supplied by only the two combustible and air inlets 1 and 2-. The rotary valve, the essential of which is that it shall have maximum port area with minimum waste of combustible due to clearance losses obtainable by a valve embracing the cylinder consists merely of the ring provided with gear teeth on its exterior surface. It is provided at suitable intervals with passages which curve throu h 90 degrees, so that they pass from one sur ace of the ring, which c0- acts with the ports w to the other surface, whichco-acts with the ports I? of the cylinder, with a minimum of constriction and with a minimum of volume, that no appreciable quantity of is wasted or lost as the result of becoming trapped in it when the valve closes. The rotary valve is caused to set firmly by the pressure of a ring 7 which presses against it under the action of a spring 8, wound around a pin 9 rigid in a lug 10 on the cylinder casting. By accurately surfacing the member 7 upon the surfaces \lllCll bear upon the rotary valve, and upon the cylinder, an. accurate and gas-tight fit can be obtained.

It will be seen that many different ways of constructing a rotary valve of this nature are practicable, provided always that it has the essentials above indicated, which are apparently most satisfactorily brought about by havinga series of small ducts in the rotary valve which turn through 90 degrees, and co-act on the one hand with the ported part of and passpasses along the passurface of the cylinder, and on the other hand with a ported surface of a combustible trunk.

A particular advantage of the rotary valve with two surfaces at right angleslies in the the ports into the cylinder andthe ports in 0 the gas duct.,/

In the form shown in the drawings the valve is 'rotated by co-action of its geared surface with gear Wheels 11 mountedupon' a lay shaft 12, operated by Worm gearing 13.

15 In the form of power unit described, the gas or combustible or inlet ports'have been described as disposedat the inner-extremities of the cylinders; This is, however, only employed in'j as far as it is advantageous as allowing simplified constructions of combusf tible and air trunks, and reducing the length and number of the same.

It will be understood that the application of the rotary valve'is not limited to a power unit of the kind illustrated, but may, as

before indicated, be applied'in many differ- 'ent,- ways.

,The water jackets which are provided around the cylinders and exhaust valve ports may be of any suitable type, and

arepreferably constructed where they surround the .cylinder with cooling ribs, which act not only to distribute the cooling medium more eflectively, but act to assist cooling by 3,5 conduction through them. Suchribs are indicated at 14 in Figsxl'and 4, and are pref erably composed of a multi-thread spiral of high pitch. They maybe formed by casting them upon the cylinder. r y

The operation of the engine isas; follows :Assu ming the unit shown in section in Fig, 1 to beconsidered, and an explosion to have occurred in the, lower cylinder, the pistons are moved apart, this motion acting to compress the charge which is in the cylinder nearest the top of the sheet, and after a short travel, the piston 0 will uncover the exhaust ports, and exhaustion will .com-

mence. The continued motion of the up per piston will uncover the combustible in let port, but no mixture will enter, owing to the valve not 'yet being open. Further motion of the upper-piston uncovers the scavenging air ports, and scavenging ensues and continues until returnof the piston cuts ofi-the scavenging supply at this moment, i

and just as the exhaust ports are being covered, the rotary valve 0 ens, andcompressed rich mixture enters. ontinue'd motion of the piston closes the mixture inlet ports,

compression ensues, and explosion, when the cycle re-commences.

- Witnesses "It will be seen that the cycle of operations in the two cylinders of each unit is displaced by 180 degrees, as also is the opening of'the' rotary valve. It will be seen that in this cycle, the cushion of air isintroduced ing exhaust products which must beeflectrve in avoiding loss of mixture and premature ignition, by contact withthe burned charge.

trated are both concaved, and have the radius of curvature above referred to, for the purpose of avoiding eddies, although, as indicated, only they pistond is essentially so formed. i

An engine as shown is particularly advantageous, as being one in which the construction and arrangement'ofthe operations are as small as possible, the reactions due to acceleration and retardation of moving parts are balanced, and negative work is practically avoided.

It will be understood that several powerunits, such as are indicated, may be combined, as for marine purposes, to act inany number desired upon the same crank shaft, such combinations producing remarkably balanced power systems, in which the varia- Having now described my invention what I claim as new and desire to secure by Letters Patent is a A scavenging internal combustion engine having acylinder, with a ring ofexhaust ports at one end of the same, and aring of gaseous combustible and a ring ofscavenging air inletports at the other end, two pis tons adapted'to move oppositely in said cylinder, and the one adapted to uncover the a rotary ring valvejembracing the ring of said two rings of ports nearer thecenter of said cylinder, and having a surface substanembraces the cylinder ports, these two sur faces being connected ducts, and a. as

in presence 0 two witnesses. v.

WILLIAM "JOSEPH srrzcn 4 OYRIL F. L, Nnnsnr R. A. OU'IHWAITE.

of the cycle are such that stresses and variations of stress transmitted to the crank shaft exhaust ring of ports, and the other to un-' cover the two other rings of ports aforesaid,

ductin proximity to saidcylinder provi ed I angular movement to place the: i

between the incoming charge and the outg'o- The piston heads in the form of engine illustion of crank efiort is reduced to a minimum.

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'tially perpendicular-1o the surface which In testilnon whereof, I aflix my signature 

